Related art shows several methods and apparatus used for collecting position information that can be used in conjunction with audio-visual systems to provide automatic follow-spot and other audio-visual applications in theatre stage, cinema and television studios, retail stores, exhibition spaces and locations of the like. Several such methods and apparatus are based on systems for the triangulation of sound waves or radio waves. These systems require that an emitter or, for other systems a receptor, be placed at all times on the object of which position information is collected. Calibration of these systems can be difficult, especially when the objects are positioned in the vicinity of reflective surfaces. Another set back or these systems is the limited number of objects that can be tracked simultaneously due to restrictions on available bandwidth for such systems.
Other methods and apparatus are based on the recognition of visual signals. U.S. Pat. No. 5,023,709 to Kita, the content of which is incorporated herein by reference thereto, discloses an automatic follow-up lighting system for automatically following an object having a mark that can reflect light in the coaxial direction when a light or infrared radiant is applied to the object. This system requires that each projector be coupled to an infrared TV camera and an electrically powered yoke or turntable, and that the object wears a mark that must remain visible at all times by a camera for the system to be effective, which is not always possible, particularly when setting elements are located on stage.
Related art shows several examples of methods for collecting position information using electrical field sensing devices, mostly in the field of capacitive touchpads which emulate a mouse or keyboard by tracking a single finger. These typically measure the capacitance of or between elongated wires which are laid out in row and columns (X-Y). A thin dielectric is interposed between the row and column layers. Presence of a finger perturbs the self or mutual capacitance for nearby electrodes. Since most of these technologies use projective row and columns sensors which integrate on one electrode the proximity of all objects in a particular row or column, they cannot uniquely determine the positions of two or more objects.
Multi-electrode capacitive sensors having a plurality of electrodes disposed about predetermined sensing area can determine the position of an object adjacent the area and, by making multiple measurements over a period of time, can determine the direction and speed of motion of the object.
Capacitive Sensors are readily commercially available such as the QT60000 FAMILY QMatrix TOUCH integrated circuit (“ICs”) by QRG Ltd., that can be used for charge-transfer capacitive matrix keypanel sensing. The QT60000 family features charge-transfer (“QT”) devices designed for touch sensing on 4, 16, 32, 48 or 64 keys when used in conjunction with a simple scanned, passive X-Y matrix. The Qmatrix IC employs transverse charge-transfer sensing in a matrix format that minimizes the number of required connections to the matrix. This product can project keypad keys through almost any dielectric up to thicknesses of 5 cm or more. Touch pads are made using simple 2-part interleaved electrodes of almost any conductor (e.g., copper, carbon, clear ITO, or screened silver on the rear of a panel). These shapes can be created using ordinary PCBs, flex circuits, or clear film. Key sizes, shapes and placement are almost entirely arbitrary and can be mixed within a panel. On 16-key devices and larger, the sensitivity of each key can be set individually using a serial communications port from a host microcontroller or computer. The devices are designed for appliances, kiosks, control panels, portable instruments, machine tools, or similar products that are subject to a variety of environmental influences or vandalism. [See http://www.qprox.com/products/]
U.S. Pat. No. 6,323,846 to Westerman, the content of which is incorporated herein by reference thereto, discloses a multi-touch surface for detecting a spatial arrangement of multiple touch devices than can be used for simultaneously tracking multiple contact points, as a manual data input for computer related applications replacing keyboard, mouse, keypad and stylus altogether. The multi-touch surface apparatus comprises a plurality of two-dimensional arrays of capacitance sensing devices arranged in groups. In this system, the sensing device is sensitive to changes in self-capacitance brought about by changes in proximity of a touch device to the sensing device. The sensing devices within a group have their output nodes connected together and share the same integrating capacitor to accumulate charge transferred during multiple consecutive switching of the series connected switching means; the same charge depletion switch, and the same voltage-to-voltage translation circuitry connected to the output node of the series-connected switching means which produces a voltage representative of the proximity of the touch device to the sensing device. The arrangement taught in U.S. Pat. No. 6,323,846 B1 does not permit a fully modular construction of the sensing devices, which modularity is required to cover large surfaces at reasonable manufacturing cost, and to enable an easy error-detection or default detection, and maintenance over a long useful life, in form of replacement of defaulting sections. This invention requires the use of a touch device or layer interacting with the sensing device, and does not concern applications where objects are directly in contact with the sensing surface.
What is needed, therefore, is a system, method or apparatus for collecting information on the geographic positions of several moving or immobile objects simultaneously, wherein such positioning and movement information can be used as input information by media control systems.